1. Field of the Invention
The invention relates to traveling water screens for screening debris and fish from water, and more particularly to an improved basket for a traveling water screen.
2. Reference to Prior Art
Traveling water screens have been used for many years in applications in which it is desired to screen debris and fish from large volumes of water. A typical application is in an industrial facility or power plant which requires a large volume of cooling water. Ordinarily, water for this purpose is taken from a river or lake through an inlet water channel. Debris and fish enter the channel with the water flowing into channel and must be screened out of the water to prevent debris from clogging the condenser tubes and to prevent the fish from being killed by heat and impingement on the condenser tubes and other parts of the cooling system.
U.S. Pat. Nos. 4,582,601, 4,360,426 and 3,868,324 illustrate traveling water screens. As shown therein, a traveling water screen typically includes an upright frame having a pair of spaced vertical support members. The support members are mounted adjacent the opposed sides of the water inlet channel, such that water flowing through the channel cannot flow around the sides of the water screen. The frame includes a boot portion adjacent the bottom of the channel and a head portion anchored in a horizontal shelf above the water in the channel. A foot shaft is supported for rotation at the boot portion. A head shaft is supported for rotation at the head portion of the frame, and a drive motor is connected to the head shaft. A pair of endless chains are trained around sprockets mounted on the head and foot shafts. A plurality of screen baskets are mounted on the chains and arranged in a continuous train for movement with the chains about a circuitous vertical path defined around the head and foot shafts. Adjacent baskets are mounted in close edge-to-edge relationship, and small gaps are provided between the baskets to provide clearance for the baskets to travel around the head and foot shafts. On the upstream side of the frame, the train of baskets moves upwardly from the foot shaft toward the head shaft, thereby forming a substantially continuous upwardly moving screen on the upstream side of the frame. The gaps between adjacent baskets permit unscreened water to flow through the traveling water screen.
Each basket includes spaced apart upper and lower lip beams, a pair of spaced apart end plates at opposite ends of the lip beams, and a water screen extending between the end plates and the upper and lower lip beams. The lower lip beam can include an elongated, upwardly opening channel upstream of the water screen for recovering fish trapped against the screen. The fish are captured in the channel as the basket moves upwardly on the upstream side of the frame. When the basket moves around the head portion of the frame, the fish and water are dumped out of the channel and into a trough in the shelf for return to the river or lake away from the water intake channel. A portion of the recovered fish are killed or injured before being deposited into the return trough.